High-k dielectric materials comprising zirconium oxide utilized in display devices

ABSTRACT

Embodiments of the disclosure generally provide methods of forming a capacitor layer or a gate insulating layer with high dielectric constant as well as low film current leakage and desired film qualities for display applications. In one embodiment, a thin film transistor structure includes a dielectric layer formed on a substrate, wherein the dielectric layer is a zirconium containing material comprising aluminum, and gate, source and drain electrodes formed on the substrate, wherein the gate, source and drain electrodes formed above or below the dielectric layer.

BACKGROUND Field

Embodiments of the present disclosure generally relate to forming adielectric layer having a high dielectric constant for display devices.More particularly, embodiments of the disclosure relate to methods forforming a high dielectric constant film layer comprising zirconium oxideby an atomic layer deposition (ALD) process for display applications.

Description of the Related Art

Display devices have been widely used for a wide range of electronicapplications, such as TV, monitors, mobile phone, MP3 players, e-bookreaders, personal digital assistants (PDAs) and the like. The displaydevice is generally designed for producing a desired image by applyingan electric field to a liquid crystal that fills a gap between twosubstrates (e.g., a pixel electrode and a common electrode) and hasanisotropic dielectric constant that controls the intensity of thedielectric field. By adjusting the amount of light transmitted throughthe substrates, the light and image intensity, quality and powerconsumption may be efficiently controlled.

A variety of different display devices, such as active matrix liquidcrystal display (AMLCD) or an active matrix organic light emitting diode(AMOLED), may be employed as light sources for display. In themanufacturing of display devices, an electronic device with highelectron mobility, low leakage current and high breakdown voltage, wouldallow more pixel area for light transmission and integration ofcircuitry, thereby resulting in a brighter display, higher overallelectrical efficiency, faster response time and higher resolutiondisplays. Low film qualities of the material layers, such as dielectriclayers with impurities or low film densities, formed in the device oftenresult in poor device electrical performance and short service life ofthe devices. Thus, a stable and reliable method for forming andintegrating film layers within TFT and OLED devices becomes crucial toproviding a device structure with low film leakage, and high breakdownvoltage for use in manufacturing electronic devices with lower thresholdvoltage shift and improved overall performance of the electronic device.

In particular, the interface management between a metal electrode layerand the nearby insulating materials becomes critical as impropermaterial selection of the interface between the metal electrode layerand the nearby insulating material may adversely result in undesiredelements diffusing into the adjacent materials, which may eventuallylead to current short, current leakage or device failure. Furthermore,the insulating materials with different higher dielectric constantsoften provide different electrical performance, such as providingdifferent capacitance in the device structures. Selection of thematerial of the insulating materials not only affects the electricalperformance of the device, incompatibility of the material of theinsulating materials to the electrodes may also result in film structurepeeling, poor interface adhesion, or interface material diffusion, whichmay eventually lead to device failure and low product yield.

In some devices, capacitors, e.g., a dielectric layer placed between twoelectrodes, are often utilized and formed to store electric charges whenthe display devices are in operation. The capacitor as formed isrequired to have high capacitance for display devices. The capacitancemay be adjusted by changing of the dielectric material and dimension ofthe dielectric layer formed between the electrodes and/or thickness ofthe dielectric layer. For example, when the dielectric layer is replacedwith a material having a higher dielectric constant, the capacitance ofthe capacitor will increase as well. As the resolution requirement fordisplay devices is increasingly challenging, e.g., display resolutiongreater than 800 ppi, only limited areas remain in the display devicesto allow forming capacitors therein to increase electrical performance.Thus, maintaining the capacitor formed in the display devices in aconfined location with a relatively small area has become crucial.

Therefore, there is a need for improved methods for forming a dielectriclayer with a high dielectric constant with desired film qualities andlow leakage for manufacturing display devices that produce improveddevice electrical performance.

SUMMARY

Embodiments of the disclosure generally provide methods of forming adielectric layer with a high dielectric constant as well as desired filmqualities and low film leakage by an atomic layer deposition process fordisplay applications. In one embodiment, a thin film transistorstructure includes a dielectric layer formed on a substrate, wherein thedielectric layer is a zirconium containing material comprising aluminum,and gate, source and drain electrodes formed on the substrate, whereinthe gate, source and drain electrodes are formed above or below thedielectric layer.

In another embodiment, a method for forming a composite film layer fordisplay devices includes performing an ALD process to form a compositefilm layer comprising a first layer and a second layer disposed on asubstrate, the first layer comprises doped aluminum zirconium containinglayer formed on the substrate and the second layer comprises zirconiumcontaining layer.

In yet another embodiment, a device structure utilized in a displaydevice includes a capacitor structure having a capacitor layer formedbetween two electrodes in a display device, wherein the capacitor layeris an aluminum doped ZrO₂ layer having an amorphous structure with adielectric constant between about 15 and about 25.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentdisclosure are attained and can be understood in detail, a moreparticular description of the disclosure, briefly summarized above, maybe had by reference to the embodiments thereof which are illustrated inthe appended drawings.

FIG. 1 depicts a sectional view of a processing chamber that may be usedto deposit a high dielectric constant dielectric layer in accordancewith one embodiment of the present disclosure;

FIG. 2 depicts a process flow diagram of one embodiment of a method offorming a high dielectric constant film layer on a substrate;

FIGS. 3A-3C depict a sectional view of one example of a portion of athin film transistor device comprising a capacitor structure having ahigh dielectric constant film layer of FIG. 2 formed therein;

FIG. 4 depicts a process flow diagram of one embodiment of a method offorming a composite film layer with high dielectric constant on asubstrate;

FIGS. 5A-5C depict a sectional view of one example of a portion of athin film transistor device structure having a composite film layer withhigh dielectric constant of FIG. 4 formed therein;

FIG. 6A-6B are sectional views of a capacitor structure formed in adisplay device structure;

FIG. 7A is a cross sectional view of one example of a display devicestructure with a capacitor structure formed therein;

FIG. 7B is a cross sectional view of another example of a display devicestructure with a capacitor structure formed therein; and

FIG. 8 is a sectional view of one example of a display device structurewith a capacitor structure having a composite film layer with highdielectric constant formed therein.

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe figures. It is contemplated that elements and features of oneembodiment may be beneficially incorporated in other embodiments withoutfurther recitation.

It is to be noted, however, that the appended drawings illustrate onlyexemplary embodiments of this disclosure and are therefore not to beconsidered limiting of its scope, for the disclosure may admit to otherequally effective embodiments.

DETAILED DESCRIPTION

Embodiments of the disclosure generally provide methods of forming ahigh dielectric constant film layer with enhanced electricalperformance, such as high capacitance and low leakage for displaydevices. Such high dielectric constant film layer (e.g., dielectricconstant greater than 10) may be formed as a capacitor or any suitablestructures in display devices. The dielectric layer may be manufacturedby an atomic layer deposition (ALD) process that may provide a filmlayer with low defect density, low impurities, low film leakage and highdielectric constant. The high dielectric constant film layer formed bythe ALD process may be utilized in any insulating structure and/orcapacitor structures in TFT devices or OLED devices. In one example, thehigh dielectric constant film layer comprises zirconium containingmaterial, such as zirconium oxide (ZrO₂), with a dielectric constantgreater than 10, such as at least between about 15 and 45, such asbetween about 15 and 25. The zirconium containing material in the highdielectric constant film layer may further include dopants to render thehigh dielectric constant film layer as an amorphous structure. Oneexemplary dopant may be an aluminum containing dopant. The zirconiumcontaining material comprising aluminum dopant may have a dielectricconstant at a relative low range (e.g., between about 15 and 25) whilemaintaining low film leakage. The zirconium containing materialcomprising aluminum dopant may be used in any suitable layers, such as agate insulating layer, a capacitor layer formed between two electrodes,an inter-insulating layer, an etching stop layer or an interfaceprotection layer in display devices for electric performance enhancementand improvement.

In some examples, the zirconium containing material as described in thisdisclosure may be exchanged or replaced with hafnium (Hf) containingmaterial, including hafnium oxide, doped hafnium, doped hafnium oxide orthe like. In some other examples, the zirconium containing material asdescribed in this disclosure may be exchanged or replaced with aluminum(Al) containing material, including aluminum oxide, doped aluminum,doped aluminum oxide or the like.

Some other embodiments of the disclosure provide methods of forming acomposite film layer having a high dielectric constant with enhancedelectrical performance, such as high capacitance and low leakage fordisplay devices. Such high dielectric constant composite film layer(e.g., dielectric constant greater than 10 and/or 25) may be formed as acapacitor or any suitable structures in display devices. The compositefilm layer with high dielectric constant may be manufactured by anatomic layer deposition (ALD) process that may provide a film layer withlow defect density, low impurities, low film leakage and high dielectricconstant. The composite film layer with high dielectric constant formedby the ALD process may be utilized in any insulating structure and/orcapacitor structures in TFT devices or OLED devices. In one example, thecomposite film layer with high dielectric constant comprises a firstportion of the film layer with zirconium containing material, such aszirconium oxide (ZrO₂), in cubic, tetragonal structures or mix of cubicand tetragonal structures, providing the composite film layer with highdielectric constant greater than 25. The composite film layer with highdielectric constant further comprises a second portion of the film layerwith zirconium containing material including dopants so as to render thezirconium containing material as an amorphous structure, providing thedoped the zirconium containing material with a dielectric constantgreater than 10 with low film leakage. One exemplary dopant may be analuminum containing dopant. The composite film layer with highdielectric constant may be used in any suitable layers, such as a gateinsulating layer, a capacitor layer formed between two electrodes, aninter-insulating layer, an etching stop layer or an interface protectionlayer in display devices for electric performance enhancement andimprovement.

FIG. 1 is a schematic cross sectional view of an ALD (atomic layerdeposition) chamber 100 that may be used to perform a depositiondescribed herein. It is contemplated that other deposition systems maybe alternatively utilized. The ALD deposition process may be utilized toform a dielectric layer, such as an insulating layer, a gate insulatinglayer, an etch stop layer, an interlayer insulator, a dielectric layerfor capacitor or passivation layer in display devices as describedherein. The chamber 100 generally includes a chamber body 101, a lidassembly 104, a substrate support assembly 106, and a process kit 150.The lid assembly 104 is disposed on the chamber body 101, and thesubstrate support assembly 106 is at least partially disposed within thechamber body 101. The chamber body 101 includes a slit valve opening 108formed in a sidewall thereof to provide access to the interior of theprocessing chamber 100. In some embodiments, the chamber body 101includes one or more apertures that are in fluid communication with avacuum system (e.g., a vacuum pump). The apertures provide an egress forgases within the chamber 100. The vacuum system is controlled by aprocess controller to maintain a pressure within the processing chamber100 suitable for ALD processes. The lid assembly 104 may include one ormore differential pumps and purge assemblies 120. The differential pumpand purge assemblies 120 are mounted to the lid assembly 104 withbellows 122. The bellows 122 allow the pump and purge assemblies 120 tomove vertically with respect to the lid assembly 104 while stillmaintaining a seal against gas leaks. When the process kit 150 is raisedinto a processing position, a compliant first seal 186 and a compliantsecond seal 188 on the process kit 150 are brought into contact with thedifferential pump and purge assemblies 120. The differential pump andpurge assemblies 120 are connected with a vacuum system (not shown) andmaintained at a low pressure.

As shown in FIG. 1, the lid assembly 104 includes a RF cathode 110 thatcan generate a plasma of reactive species within the chamber 100 and/orwithin the process kit 150. The RF cathode 110 may be heated by electricheating elements (not shown), for example, and cooled by circulation ofcooling fluids, for example. Any power source capable of activating thegases into reactive species and maintaining the plasma of reactivespecies may be used. For example, RF or microwave (MW) based powerdischarge techniques may be used. The activation may also be generatedby a thermally based technique, a gas breakdown technique, a highintensity light source (e.g., UV energy), or exposure to an x-raysource.

The substrate support assembly 106 can be at least partially disposedwithin the chamber body 101. The substrate support assembly 106 caninclude a substrate support member or susceptor 130 to support asubstrate 102 for processing within the chamber body. The susceptor 130may be coupled to a substrate lift mechanism (not shown) through a shaft124 or shafts 124 which extend through one or more openings 126 formedin a bottom surface of the chamber body 101. The substrate liftmechanism can be flexibly sealed to the chamber body 101 by a bellows128 that prevents vacuum leakage from around the shafts 124. Thesubstrate lift mechanism allows the susceptor 130 to be moved verticallywithin the ALD chamber 100 between a lower robot entry position, asshown, and processing, process kit transfer, and substrate transferpositions. In some embodiments, the substrate lift mechanism movesbetween fewer positions than those described.

In some embodiments, the substrate 102 may be secured to the susceptorusing a vacuum chuck (not shown), an electrostatic chuck (not shown), ora mechanical clamp (not shown). The temperature of the susceptor 130 maybe controlled (by, e.g., a process controller) during processing in theALD chamber 100 to influence temperature of the substrate 102 and theprocess kit 150 to improve performance of the ALD processing. Thesusceptor 130 may be heated by, for example, electric heating elements(not shown) within the susceptor 130. The temperature of the susceptor130 may be determined by pyrometers (not shown) in the chamber 100, forexample.

As shown in FIG. 1, the susceptor 130 can include one or more bores 134through the susceptor 130 to accommodate one or more lift pins 136. Eachlift pin 136 is mounted so that the lift pin 136 may slide freely withina bore 134. The support assembly 106 is movable such that the uppersurface of the lift pins 136 can be located above the substrate supportsurface 138 of the susceptor 130 when the support assembly 106 is in alower position. Conversely, the upper surface of the lift pins 136 islocated below the substrate support surface 138 of the susceptor 130when the support assembly 106 is in a raised position. When contactingthe chamber body 101, the lift pins 136 push against a lower surface ofthe substrate 102, lifting the substrate off the susceptor 130.Conversely, the susceptor 130 may raise the substrate 102 off of thelift pins 136.

In some embodiments, the susceptor 130 includes process kit insulationbuttons 137 that may include one or more compliant seals 139. Theprocess kit insulation buttons 137 may be used to carry the process kit150 on the susceptor 130. The one or more compliant seals 139 in theprocess kit insulation buttons 137 are compressed when the susceptorlifts the process kit 150 into the processing position.

FIG. 2 depicts a flow diagram of one embodiment of a process 200 forforming a high dielectric constant material layer suitable for use indisplay devices, such as thin-film transistor devices or OLED devices.Such high dielectric constant material layer may be formed as acapacitor layer disposed between two metal layers to form a capacitor.Suitable examples of the high dielectric constant material layer used indisplay devices include a gate insulating layer, a capacitor layerdisposed between two metal layers, an interface layer, a dielectriclayer utilized to form a capacitor, an etch stop layer or a passivationlayer where an insulating material is needed. The high dielectricconstant material layer may be formed by an atomic layer deposition(ALD) process or plasma assisted atomic layer deposition (ALD) process(PE-ALD), which may be practiced in the processing chamber 100, asdescribed in FIG. 1, or other suitable processing chamber, or incombination thereof.

The process 200 begins at operation 202 by transferring the substrate102 into a processing chamber, such as the processing chamber 100 (anALD chamber) depicted in FIG. 1, to form a high dielectric constantmaterial layer, as shown in FIG. 3A. The substrate 102 may havedifferent combinations of films, structures or layers previously formedthereon to facilitate forming different device structures or differentfilm stacks on the substrate 102. The substrate 102 may be any one ofglass substrate, plastic substrate, polymer substrate, metal substrate,singled substrate, roll-to-roll substrate, or other suitable transparentsubstrate suitable for forming a thin film transistor thereon.

At operation 204, an atomic layer deposition (ALD) process is thenperformed on the substrate 102 to form a high dielectric constantmaterial layer 308 (shown in FIG. 3C) on the substrate 102 by forming afirst layer 304 on a surface 302 of the substrate 102. The first layer304 is formed by performing a first reaction by supplying a firstprecursor, with or without the reactive gaseous species, onto an uppersurface the substrate 102, as shown in FIG. 3A. The first layer 304 maybe an inorganic material containing metal. Atomic layer deposition (ALD)process is a deposition process with self-terminating/limiting growth.The ALD process yields a thickness of only a few angstroms or in amonolayer level for each cycle of deposition. The ALD process iscontrolled by sequentially distributing chemical and reactant into aprocessing chamber which is repeated in cycles. The thickness of thehigh dielectric constant material layer to be formed by the ALD processon the substrate 102 depends on the number of the reaction cycles. Thefirst reaction of the first precursor provides a first atomic layer ofmolecular layer, such as the first layer 304, being absorbed on thesubstrate 102 and the second reaction (will be described further belowat operation 206) provide a second atomic layer of molecular layer, suchas the second layer 306 shown in FIG. 3B, being absorbed on the firstlayer 304.

The first reaction may deposit the first layer 304 of the highdielectric constant material layer 308 having a thickness between about0.5 Å and about 3 Å.

In one example, the first precursor utilized in the first pulse ofreaction to form the first layer 304 includes a zirconium (Zr)containing precursor. Suitable examples of the zirconium containingprecursor include Zr-organometallic precursors, such astetrakis(ethylmethylamino)zirconium (TEMAZ),tris(dimethylamino)cyclopentadienyl zirconium (C₅H₅)Zr[N(CH₃)₂]₃, or thelike. In one particular example utilized herein, the first precursor istetrakis(ethylmethylamino)zirconium (TEMAZ).

It is believed that utilizing the Zr containing precursor to form a Zrcontaining layer as the high dielectric constant material layer 308 byan atomic layer deposition (ALD) process may provide good filmproperties, such as high thermal stability, high deposition rate, lowfilm leakage, high film density, low defect density and the like. Strongadherence of atoms in each layers and absorbability of the layers ofatoms onto the surface of substrate provide compact and secured bondingstructures in the film structures so as to render a film property with ahigh film density (compared to a chemical vapor deposition process) thatmay efficiently eliminate loose film structure in the dielectric layerthat may result in current leakage. Furthermore, the high film densitymay also prevent moisture or contaminant from penetrating therethrough.Furthermore, the slow ALD deposition rate of the monolayers formed onthe substrate also allows the atoms from each monolayer to graduallyfill in the pinholes, pores, pits or defects that may be present on thesubstrate surface so as to assist repairing the film defects on thesubstrate surface.

The first pulse of reaction lasts for a predetermined time interval. Theterm pulse as used herein refers to a dose of material injected into theprocess chamber. Between each pulse of the first precursor or/and asecond precursor and/or a reactive gaseous species, a purge gas mixture,such as a nitrogen gas, an inert gas (e.g., He or Ar) may be pulsed intothe processing chamber in between each or multiple pulses of the firstprecursor or/and a second precursor and/or a reactive gaseous species(e.g., between the different metal containing gas and the oxygencontaining gas) to remove the by-products, impurities or residualprecursor gas mixture which is unreacted/non-absorbed by the substratesurface (e.g., unreacted impurities from the reactant gas mixture orothers) so they can be pumped out of the processing chamber.

During the pulsing of the first precursor comprising Zr containingprecursor, a reactive gaseous species may be supplied simultaneouslywith, alternatively, or sequentially with the first precursor (e.g., theZr containing precursor as one example) for forming the first layer 304during the deposition process. In one example, the reactive gaseousspecies supplied simultaneously with, alternatively, or sequentiallywith the first precursor may be oxygen containing gases, such as H₂O,O₂, O₃, CO₂, H₂O₂, NO₂, N₂O, and the like. In one example, the oxygencontaining gas is O₂ or O₃. Alternatively, the reactive gaseous speciesmay be supplied after a pulse of a pump/purge gas is performed to purgeout the residual first precursor remained in the processing chamber 100.

During pulsing of the first precursor with or without the reactivegaseous species (e.g., the reactive gaseous species supplied after thefirst precursor), several process parameters are also regulated. In oneembodiment, the process pressure is controlled at between about 0.1 Torrand about 1 Torr. The processing temperature is between about 40 degreesCelsius and about 300 degrees Celsius, such as about 200 degreesCelsius. In one embodiment, the RF source power is controlled at betweenabout 500 watts and about 3500 watts, such as about 3000 Watts.

Thus, the first layer 304 shown in FIG. 3A may include Zr elements aswell as oxygen elements, after the first pulse of the first precursor aswell as the reactive gaseous species. The first layer 304 comprises Zrand oxygen elements form a first portion of the high dielectric constantmaterial layer 308.

At operation 206, after the first reaction and a pump/purge process, asecond reaction including a second precursor, with or without thereactive gaseous species, onto the first layer 304 to form a secondlayer 306 on the substrate 102, as shown in FIG. 3B. The secondprecursor is also a metal containing precursor but different from thefirst precursor. In one example, the second precursor includes aluminum.Suitable examples of the second precursor comprising aluminum may have aformula of R_(x)Al_(y)R′_(z)R″_(v) or R_(x)Al_(y)(OR′)_(z), where R, R′and R″ are H, CH₃, C₂H₅, C₃H₇, CO, NCO, alkyl or aryl group and x, y, zand v are integers having a range between 1 and 8. In anotherembodiment, the aluminum containing compound may have a formula ofAl(NRR′)₃, where R and R′ may be H, CH₃, C₂H₅, C₃H₇, CO, NCO, alkyl oraryl group and R′ may be H, CH₃, C₂H₅, C₃H₇, CO, NCO, alkyl or arylgroup. Examples of suitable aluminum containing compounds arediethylalumium ethoxide (Et₂AlOEt), triethyl-tri-sec-butoxy dialumium(Et₃Al₂OBu₃, or EBDA), trimethylaluminum (TMA), trimethyldialumiumethoxide, dimethyl aluminum isupropoxide, disecbutoxy aluminum ethoxide,(OR)₂AlR′, wherein R, R′ and R″ may be methyl, ethyl, propyl, isopropyl,butyl, isobutyl, tertiary butyl, and other alkyl groups having highernumbers of carbon atoms, and the like.

In one specific example, the second precursor comprising aluminum istrimethylaluminum (TMA).

Each reaction may deposit the second layer 306 of the high dielectricconstant material layer 308 having a thickness between about 0.5 Å andabout 3 Å.

It is believed that the second metal elements provided from the secondprecursor may be considered as a dopant doped in the high dielectricconstant material layer 308 so as to render the resultant highdielectric constant material layer 308 in an amorphous structure. A ZrO₂layer formed by an atomic layer deposition process often provides theresultant ZrO₂ in crystalline structure in cubic or tetragonal phase,providing a dielectric constant at least between about 25 and about 50.However, as the dielectric constant of a material increases, the bandgap of the material decreases, leading to high leakage current in thedevice. Thus, by providing a dopant, such as a second element, in thematerial, the crystalline structure of the material may be altered intoan amorphous state, thus lowering the dielectric constant of a certainpredetermined level so as to keep the current leakage at a desired lowlevel. For example, by providing a dopant, such as the second metalelement comprising aluminum, into the ZrO₂ structure, may render theresultant ZrO₂ structure amorphous, thus, keeping the dielectricconstant of the amorphous aluminum doped ZrO₂ at a range between about15 and about 25.

The second reaction lasts for a predetermined time interval to form thesecond layer 306 comprising aluminum. During pulsing of the secondprecursor comprising Al containing precursor, a reactive gaseous speciesmay be supplied simultaneously with, alternatively, or sequentially withthe second precursor (e.g., the Al containing precursor as one example)for forming the second 306 during the deposition process. In oneexample, the reactive gaseous species supplied simultaneously with,alternatively, or sequentially with the first precursor may be oxygencontaining gases, such as H₂O, O₂, O₃, CO₂, H₂O₂, NO₂, N₂O, and thelike. In one example, the oxygen containing gas is O₂ or O₃.Alternatively, the reactive gaseous species may be supplied after apulse of a pump/purge gas is performed to purge out the residual secondprecursor remained in the processing chamber 100.

During supplying of the second precursor with or without the reactivegaseous species (e.g., the reactive gaseous species supplied after thefirst precursor), several process parameters are also regulated. In oneembodiment, the process pressure is controlled at between about 0.1 Torrand about 1 Torr. The processing temperature is between about 40 degreesCelsius and about 300 degrees Celsius, such as about 200 degreesCelsius. The RF source power is controlled at between about 500 wattsand about 3500 watts, such as about 3000 Watts.

Thus, the second layer 306 shown in FIG. 3B may include Al elements aswell as oxygen elements, after the second pulse of the second precursoras well as the reactive gaseous species. The second layer 306 comprisesAl and oxygen elements form a second portion of the high dielectricconstant material layer 308.

It is noted that the first reaction at operation 204 and the secondreaction at operation 206 may be repeatedly performed, as indicated bythe loop 207, forming an upper most first layer 304′ and an upper mostsecond layer 306′, until a desired thickness of the overall highdielectric constant material layer 308 is reached.

At operation 208, after a number of repeating cycles of the first pulseand the second pulse of reactions at operation 204 and 206, the highdielectric constant material layer 308 is then formed on the substrate,as shown in FIG. 3C. In one example, a total of about 200 cycles ofoperation 204 and 206 may be performed to form the high dielectricconstant material layer 308. The resultant high dielectric constantmaterial layer 308 may include multiple layers of the repeating firstand second layers (the bottom first and second layer 304, 306 and theupper most first and the second layer shown as 304′, 306′) until adesired thickness 310 is reached. In one example, the desired thickness310 may be between about 25 nm and about 90 nm. The high dielectricconstant material layer 308 may have a dielectric constant between about15 and 25 and a film leakage about 1E-8A/cm² or below. The highdielectric constant material layer 308 has an aluminum dopant in a ZrO₂structure with a doping concentration between 6 atm. % and about 20 atm.% (between elements of Zr and Al).

The deposition process 200 forms the high dielectric constant materiallayer with a dielectric constant greater than 10, such as greater than15, for example between about 15 and 25. In one example, the resultanthigh dielectric constant material layer 308 is a ZrO₂ layer with Aldopants having an amorphous structure.

It is noted that the dopant may affect the range of the dielectricconstant resulted in the high dielectric constant material layer 308. Inone example, when the aluminum dopant in a ZrO₂ structure with a dopingconcentration may be controlled less than 5 atm. % (between elements ofZr and Al), which may result in the high dielectric constant materiallayer 308 has a structure in substantially crystalline structure havinga dielectric constant between about 25 and 45. In another example, thealuminum dopant in a ZrO₂ structure with a doping concentration may becontrolled between 6 atm. % and about 20 atm. % (between elements of Zrand Al), which may result in the high dielectric constant material layer308 has a structure in amorphous structure having a dielectric constantbetween about 15 and 25. In yet another example, the aluminum dopant ina ZrO₂ structure with a doping concentration may be controlled between20 atm. % and about 100 atm. % (between elements of Zr and Al), whichmay result in the high dielectric constant material layer 308 having anamorphous structure with a dielectric constant between about 9 and 15.

In some examples, the Al dopants in the high dielectric constantmaterial layer 308 could also be replaced as silicon dopants. Forexample, a silicon containing dopant, such as SiO₂, may also be used inthe ZrO₂ material to form a film layer with dielectric constant greaterthan 15, for example between about 15 and 25.

FIG. 4 depicts a flow diagram of one embodiment of a process 400 forforming a composite film layer with high dielectric constant as well aslow film leakage suitable for use in display devices, such as thin-filmtransistor devices or OLED devices. Such composite film layer with highdielectric constant may be formed as a capacitor layer disposed betweentwo metal layers to form a capacitor. Suitable examples of the compositefilm layer with high dielectric constant used in display devices includea gate insulating layer, a capacitor layer disposed between two metallayers, an interface layer, a dielectric layer utilized to form acapacitor, an etch stop layer or a passivation layer where an insulatingmaterial is needed. The high dielectric constant material layer may beformed by an atomic layer deposition (ALD) process or plasma assistedatomic layer deposition process (PE-ALD), which may be practiced in theprocessing chamber 100, as described in FIG. 1, or other suitableprocessing chamber, or in combination thereof.

The process 400 begins at operation 402 by transferring the substrate102 into a processing chamber, such as the processing chamber 100 (anALD chamber) depicted in FIG. 1, to form a composite film layer 502 witha high dielectric constant on the substrate 102, as shown in FIG. 5A.

At operation 404, an atomic layer deposition (ALD) process is thenperformed on the substrate 102 to form a first layer 510 of thecomposite film layer 502, as shown in FIG. 5A. The first layer 510 ofthe composite film layer 502 may be formed by an ALD process. The firstlayer 510 may be formed by performing a first type of reaction of theALD process by continuously pulsing precursor gas mixtures (more thanone type of precursor gas mixtures), with or without the reactivegaseous species, onto the substrate 102, as shown in FIG. 5A, formingthe first layer 510 may be an inorganic material containing metal. It isnoted that the reactive gaseous species may be pulsed simultaneously,alternatively, or sequentially with the precursor gas mixtures to formthe first layer 510 of the composite film layer 502. Between the pulsesof the reactive gaseous species and the precursor gas mixtures, apump/purge process may be performed to remove the precursor residualsfrom the processing chamber prior to another pulse.

The thickness, shown by arrows 506, of the composite film layer 502 tobe formed by the ALD process on the substrate 102 depends on the numberof the reaction cycles. In one example, the first layer 510 of thecomposite film layer 502 has a thickness between about 25 nm and about90 nm.

In one example, the precursor mixtures utilized to form the first layer510 may include alternatively or sequentially supplying a zirconiumcontaining precursor and an aluminum containing precursor with orwithout the reactive gaseous species to form an aluminum doped zirconium(Zr) containing layer. Suitable zirconium containing precursor includeZr-organometallic precursors, such astetrakis(ethylmethylamino)zirconium (TEMAZ),tris(dimethylamino)cyclopentadienyl zirconium (C₅H₅)Zr[N(CH₃)₂]₃, or thelike. In one particular example utilized herein, the zirconiumcontaining precursor is tetrakis(ethylmethylamino)zirconium (TEMAZ).

Suitable examples of the aluminum containing precursor may have aformula of R_(x)Al_(y)R′_(z)R″_(v) or R_(x)Al_(y)(OR′)_(z), where R, R′and R″ are H, CH₃, C₂H₅, C₃H₇, CO, NCO, alkyl or aryl group and x, y, zand v are integers having a range between 1 and 8. In anotherembodiment, the aluminum containing compound may have a formula ofAl(NRR′)₃, where R and R′ may be H, CH₃, C₂H₅, C₃H₇, CO, NCO, alkyl oraryl group and R′ may be H, CH₃, C₂H₅, C₃H₇, CO, NCO, alkyl or arylgroup. Examples of suitable aluminum containing compounds arediethylalumium ethoxide (Et₂AlOEt), triethyl-tri-sec-butoxy dialumium(Et₃Al₂OBu₃, or EBDA), trimethylaluminum (TMA), trimethyldialumiumethoxide, dimethyl aluminum isupropoxide, disecbutoxy aluminum ethoxide,(OR)₂AlR′, wherein R, R′ and R″ may be methyl, ethyl, propyl, isopropyl,butyl, isobutyl, tertiary butyl, and other alkyl groups having highernumbers of carbon atoms, and the like. In one specific example, thealuminum containing precursor is trimethylaluminum (TMA).

The reactive gaseous species may be oxygen containing gases, such asH₂O, O₂, O₃, H₂O₂, CO₂, NO₂, N₂O, and the like. In one example, theoxygen containing gas is O₂ or O₃.

It is believed that second metal elements, e.g., the aluminum containingdopants, formed and doped into the first layer 510 (e.g., Zr containinglayer) may be considered as dopants doped in the composite film layer502 so as to render the first layer 510 of the ZrO₂ layer as anamorphous structure. A ZrO₂ layer formed by an atomic layer depositionprocess often provides the ZrO₂ in crystalline structure in cubic ortetragonal phase or mix of cubic and tetragonal phases, providing adielectric constant at least greater than 25, such as between about 25and about 50. However, as the dielectric constant of a materialincreases, the band gap of the material decreases, leading to highleakage current in the device. Thus, higher dielectric constant, e.g.,greater than 25, of a dielectric layer is desired for the advancedtechnologies so as to provide a capacitor with higher capacitance. Incontrast, higher dielectric constant, e.g., greater than 25, of thedielectric layer also often results in high film leakage that mayeventually lead to device failure. Thus, by forming the first layer 510of the composite film layer 502 with a relatively low dielectricconstant (e.g., greater than 10 but less than 25), the composite filmlayer 502 may keep certain degree of low film leakage. Thus, byproviding a dopant, such as the aluminum dopants, formed in the firstlayer 510 of the composite film layer 502, the crystalline structure ofthe material may be altered into an amorphous state, thus lowering thedielectric constant of a certain predetermined level so as to keep thecurrent leakage at a desired low level. For example, by providingaluminum dopant into the ZrO₂ structure to form the first layer 510 mayrender the resultant ZrO₂ structure in amorphous state, thus, keepingthe dielectric constant of the amorphous aluminum doped ZrO₂ at adesired range less than 25 but above 10. Subsequently, the second layer512 of composite film layer 502 is formed by a ZrO₂ in crystallinestructure in cubic or tetragonal phase or mix of cubic and tetragonalphases (e.g., dielectric constant greater than 25) to increase thecapacitance of the resultant composite film layer 502, which will bedescribed below in detail at operation 406.

In one example, the precursor gas mixtures supplied in the first type ofreaction for forming the first layer 510 include pulsing a firstprecursor comprising Zr containing precursor with or without the oxygencontaining gas as the reactive gaseous species. In the example whereinthe oxygen containing gas is not supplied with the Zr containingprecursor, the oxygen containing gas may be supplied after the Zrcontaining precursor is supplied to the processing chamber 100 after apump/purge process. After the first precursor comprising a Zr containingprecursor is pulsed, a second precursor comprising Al containingprecursor may then be pulsed to continue forming the first layer 510,forming the first layer 510 as an aluminum doped ZrO₂ layer. Similarly,the second precursor comprising an Al containing precursor may besupplied with or without the oxygen containing gas as the reactivegaseous species. In the example wherein the oxygen containing gas is notsupplied with the Al containing precursor, the oxygen containing gas maybe supplied after the Al containing precursor is supplied to theprocessing chamber 100 after a pump/purge process. It is noted that thesequence of supplying the first precursor comprising a Zr containingprecursor and the second precursor comprising an Al containing precursormay be reversed or in any order as needed. It is noted that the reactivegaseous species always serves as a reactive species to be suppliedbetween each pulse of the first and the second precursors to form ZrO₂or Al doped ZrO₂.

The pulses of the first type of reaction at operation 404 last for apredetermined time interval. The term pulse as used herein refers to adose of material injected into the process chamber. Between each pulseof the first precursor or/and a second precursor and/or a reactivegaseous species, a purge gas mixture, such as a nitrogen gas, an inertgas (e.g., He or Ar) may be pulsed into the processing chamber inbetween each or multiple pulses of the first precursor or/and a secondprecursor and/or a reactive gaseous species (e.g., between the differentmetal containing gas and the oxygen containing gas) to remove theby-products, impurities or residual precursor gas mixture which isunreacted/non-absorbed by the substrate surface (e.g., unreactedimpurities from the reactant gas mixture or others) so they can bepumped out of the processing chamber.

The first layer 510 of the composite film layer 502 may have adielectric constant greater than 10, such as between 15 and 25 and afilm leakage about 1E-8A/cm² or below. The first layer 510 of thecomposite film layer 502 has an aluminum dopant in a ZrO₂ structure witha doping concentration between about 6 atm. % and about 20 atm. %(between elements of Zr and Al).

During the first type of reaction of forming the first layer 510 atoperation 404, several process parameters are also regulated. In oneembodiment, the process pressure is controlled at between about 0.1 Torrand about 1 Torr. The processing temperature is between about 40 degreesCelsius and about 300 degrees Celsius, such as about 200 degreesCelsius. The RF source power is controlled at between about 500 wattsand about 3500 watts, such as about 3000 Watts.

It is noted that the dopant may affect the range of the dielectricconstant resulted in the first layer 510. In one example, when thealuminum dopant in a ZrO₂ structure with a doping concentration may becontrolled less than 5 atm. % (between elements of Zr and Al), which mayresult in the resultant first layer 510 has a structure in substantiallycrystalline structure having a dielectric constant between about 25 and45. In another example, the aluminum dopant in a ZrO₂ structure with adoping concentration may be controlled between 5 atm. % and about 20atm. % (between elements of Zr and Al), which may result in theresultant first layer 510 has a structure in amorphous structure havinga dielectric constant between about 15 and 25. In yet another example,the aluminum dopant in a ZrO₂ structure with a doping concentration maybe controlled between 20 atm. % and about 100 atm. % (between elementsof Zr and Al), which may result in the resultant first layer 510 has astructure in amorphous structure having a dielectric constant betweenabout 9 and 15.

In some examples, the Al dopants in the first layer 510 could also bereplaced as silicon dopants. For example, a silicon containing dopant,such as SiO2, may also be used in the ZrO2 material to form a film layerwith dielectric constant greater than 15, for example between about 15and 25.

At operation 406, after the first layer 510 of the composite film layer502 is formed, the second layer 512 is formed on the first layer 510 bya second type of reaction of the ALD process performed to form thecomposite film layer 502. The second layer 512 has a thickness shown byarrows 514. As discussed above, in order to maintain the resultantcomposite film layer 502 with desired high dielectric constant levelwhile having the desired low film leakage, the second layer 512 isformed to have predominately ZrO₂ layer in crystalline structure incubic or tetragonal phase or mix of cubic and tetragonal phases,providing a dielectric constant at least greater than 25, such asbetween about 35 and about 50. The second layer 512 of ZrO₂ layer formedby the atomic layer deposition process often provides the resultant ZrO₂in crystalline structure (e.g., in cubic and/or tetragonal phase orcombinations thereof) so as to provide the resultant composite filmlayer 502 with desired two-layer structure including amorphous andcrystalline structures.

It is noted that by controlling minimum Al dopant concentration (e.g.,less than 5 atomic %), a crystalline structure (e.g., in cubic and/ortetragonal phase or combinations thereof) of the second layer 512 mayalso be obtained

It is believed that utilizing the Zr containing layer as the secondlayer 312 of the resultant composite film layer 502 by an atomic layerdeposition (ALD) process may provide good film properties, such as highthermal stability, high deposition rate, high film density, low defectdensity and the like.

In one example, the precursor gas mixture supplied in the second type ofreaction for forming the second layer 512 includes pulsing the precursorcomprising a Zr containing precursor with or without the oxygencontaining gas as the reactive gaseous species. In the example whereinthe oxygen containing gas is not supplied with the Zr containingprecursor, the oxygen containing gas may be supplied after the Zrcontaining precursor is supplied to the processing chamber 100 after apump/purge process.

During the supply of the precursor comprising a Zr containing precursor,a reactive gaseous species may be supplied simultaneously with,alternatively, or sequentially with the precursor (e.g., the Zrcontaining precursor as one example) for forming the second layer 512during the deposition process. The reactive gaseous species may besupplied after a pulse of a pump/purge gas is performed to purge out theresidual first precursor remained in the processing chamber 100. Thepulses of the second type of reaction at operation 406 last for apredetermined time interval. Between each pulse of the precursor and/ora reactive gaseous species, a purge gas mixture, such as a nitrogen gas,an inert gas (e.g., He or Ar) may be pulsed into the processing chamberin between each or multiple pulses of the precursor and/or a reactivegaseous species (e.g., between the metal containing gas and the oxygencontaining gas) to remove the impurities or residual precursor gasmixture which is unreacted/non-absorbed by the substrate surface (e.g.,unreacted impurities from the reactant gas mixture or others) so theycan be pumped out of the processing chamber. It is noted that thereactive gaseous species always serves as a reactive species to besupplied between each pulse of precursor to form ZrO₂ as the secondlayer 512.

The second layer 512 of the composite film layer 502 may have adielectric constant greater than 25, such as between 25 and 50, In oneexample, the second layer 512 of the composite film layer 502 has athickness between about 25 nm and about 90 nm

During the second type of reaction of forming the second layer 512 atoperation 406, several process parameters are also regulated. In oneembodiment, the process pressure is controlled at between about 0.1 Torrand about 1 Torr. The processing temperature is between about 40 degreesCelsius and about 300 degrees Celsius, such as about 200 degreesCelsius. The RF source power is controlled at between about 500 wattsand about 3500 watts, such as about 3000 watts.

In one example, the second precursor comprising aluminum supplied atoperation 404 to form the first layer 510, e.g., the aluminum doped ZrO₂layer, may be eliminated from supplying when the first layer 510 hasreached to the desired thickness, thus leaving the first precursorcomprising zirconium continuously pulsing and supplying (with or withoutthe reactive species) to form the second layer 512 predominatelycomprising zirconium oxide. It is noted that the reactive gaseousspecies always serves as a reactive species to be supplied between eachpulse of the first precursor comprising Zr and/or the second precursorcomprising Al to form ZrO₂ or Al doped ZrO₂.

By adjusting thickness ratio between first and the second layers 510,512, the resultant composite film layer 502 may have an average filmdielectric constant between about 15 and about 35.

It is noted that the order of the first and the second layer 510, 512formed on the substrate 102 may be in any order or may be for as manytimes as possible. For example, the composite film layer 502 may has asmany repeating first and second layers 510, 512 as needed in any order.

In some examples, the composite film layer 502 in FIG. 5A-5B or the highdielectric constant material layer 308 in FIG. 3A-3C may also be formedas aluminum containing layers or hafnium containing layers, rather thanZr containing layers.

In one example, an additionally aluminum containing layer, such as Al₂O₃and Al₂N₃, may be formed at the interface between the substrate and thecomposite film layer 502, or between the high dielectric constantmaterial layer 308 and the substrate, or above the composite film layer502, or above the high dielectric constant material layer 308 in thedevice structure as needed.

Additionally, instead of the additionally aluminum containing layerformed at the interface, above or below the first and the second layers510, 512, an additional layer 515 may be formed on the second layer 512,as shown in FIG. 5C. Similarly, the additional layer 515 may also beformed by ALD or PE-ALD process. As discussed above, in order tomaintain the resultant composite film layer 502 with desired highdielectric constant level while having the desired low film leakage, theadditional layer 515 formed on the second layer 512 may be a heavilyaluminum doped ZrO₂ layer, that renders the additional layer 515 isamorphous state comprising mostly aluminum oxide. The additional layer515 may have a dielectric constant between about 9 and about 15. Theconcentration of Al in the ZrO2 layer is greater than 20 atomic %, suchas between about 20 atomic % and about 100 atomic %.

It is noted that the heavily doped ZrO₂ layer may be formed below thefirst layer 510 above the substrate 103, as shown in dotted line as theadditional layer 517 in FIG. 5C. Furthermore, the order for forming thefirst and the second layer 510, 512 may be in any arrangement, such asforming the second layer 512 first in contact with the substrate 102 (orthe additional layer 517) then followed with the first layer 510 on thesubstrate 512 as needed.

FIG. 6A depicts a simple capacitor structure 606 (e.g., a MIM(metal-insulating-metal) structure) that may be formed on the substrate102 utilized in in display devices. The capacitor structure 606 includesa top electrode 604 and a bottom electrode 602 having the composite filmlayer 502 disposed therebetween. The composite film layer 502 includesthe first layer 510 of aluminum doped ZrO₂ and the second layer 512 ofZrO₂. The composite film layer 502 provides a high dielectric constant(e.g., a portion between 35 and 50 and a portion between 15 and 25) toserve as a capacitor layer between the electrodes 604, 602 to form thecapacitor structure 606. The composite film layer 502 serving as thecapacitor layer in the capacitor structure 606 may also in form of anynumbers of the layers as needed. Alternatively, the capacitor structure606 may have the high dielectric constant material layer 308, asdescribed above in FIG. 3, as a capacitor layer disposed in between toform the capacitor structure 606, as shown in FIG. 6B. The capacitorlayer comprises a high-k material comprising ZrO₂ including aluminumdopants. The high dielectric constant material layer 308 serving as acapacitor layer in a capacitor structure may also in form of any numbersof the layers as needed.

FIG. 7A depicts an example of a TFT structure 750 utilizing thecomposite film layer 502 in FIG. 5A-5B or the high dielectric constantmaterial layer 308 in FIG. 3A-3C in the TFT structure 750 to form acapacitor. A portion of the exemplary TFT device structure 750 isdepicted in FIG. 7A formed on the substrate 102. The TFT devicestructure 750 comprises a low temperature polysilicon (LTPS) TFT forOLED device. The LTPS TFT device structure 750 are MOS devices builtwith a source region 709 a, channel region 708, and drain region 709 bformed on the optically transparent substrate 102 with or without anoptional insulating layer 704 disposed thereon. The source region 709 a,channel region 708, and drain region 709 b are generally formed from aninitially deposited amorphous silicon (a-Si) layer that is typicallylater thermal or laser processed to form a polysilicon layer. Thesource, drain and channel regions 709 a, 708, 709 b can be formed bypatterning areas on the optically transparent substrate 102 and iondoping the deposited initial a-Si layer, which is then thermally orlaser processed (e.g., an Excimer Laser Annealing process) to form thepolysilicon layer. A gate insulating layer 706 (e.g., the insulatinglayer or the composite film layer 502 of FIGS. 5A-5B with highdielectric constant formed by the process 400 of FIG. 4 or the highdielectric constant material layer 308 in FIG. 3A-3C formed by theprocess 200 of FIG. 2) may be then deposited on top of the depositedpolysilicon layer(s) to isolate a gate electrode 714 from the channelregion 708, source region 709 a and drain regions 709 b. The gateelectrode 714 is formed on top of the gate insulating layer 706. Thegate insulating layer 706 is also commonly known as a gate oxide layer.A capacitor layer 713 (e.g., may also be the insulating layer or thecomposite film layer 502 of FIGS. 5A-5B with high dielectric constantformed by the process 400 of FIG. 4 or the high dielectric constantmaterial layer 308 in FIG. 3A-3C formed by the process 200 of FIG. 2)and device connections are then made through the insulating material toallow control of the TFT device. As indicated by the circles in FIG. 7A,the gate insulating layer 706 and the capacitor layer 713 in the TFTdevice structure 750 may also be fabricated by the composite film layer502 with high dielectric constant as well as the low film leakageincluding the first layer 510 and the second layer 512 formed thereon orby the high dielectric constant material layer 308 including the firstlayer 304 and the second layer 306.

The device structure 750 of FIG. 7A is just partially formed for ease ofdescription and explanation regarding to where the composite film layer502 and the high dielectric constant material layer 308 may be utilizedin some locations in the device structure 750 utilized to form eitherthe gate insulating layer 706 or the capacitor layer 713, or both, inthe device structure 750.

After the capacitor layer 713 is formed, an interlayer insulator 730 maybe formed on the capacitor layer 713. The interlayer insulator 730 maybe any suitable dielectric layer, such as silicon oxide or siliconnitride materials. The interlayer insulator 730 may be in form of asingle layer formed on the capacitor layer 713. Alternatively, theinterlayer insulator 730 may be in form of multiple layers as needed fordifferent device requirements. In the example depicted in FIG. 7A, theinterlayer insulator 730 includes a first dielectric layer 732 ofsilicon nitride formed on a second dielectric layer 734 of a siliconoxide layer. Subsequently, a source-drain metal electrode layer 710 a,710 b is then deposited, formed and patterned in the interlayerinsulator 730, the capacitor layer 713 and the gate insulating layer 706electrically connected to the source region 709 a and drain regions 709b.

After the source-drain metal electrode layer 710 a, 710 b is patterned,the planarization layer 735 is then formed over the source-drain metalelectrode layer 710 a, 710 b. The planarization layer 735 may befabricated from polyimide, benzocyclobutene-series resin, spin on glass(SOG) or acrylate. The planarization layer 735 is later patterned toallow a pixel electrode 716 to be formed on and filled in theplanarization layer 735, electrically connecting to the source-drainmetal electrode layer 710 a, 710 b.

In this example depicted in FIG. 7A, the capacitor layer 713 is formedon the gate electrode 714 extending to a capacitor structure 712 (e.g.,a MIM (metal-insulating-metal) structure) formed between an upperelectrode 710 and a lower electrode 707. The upper electrode 710 may belaterally coupled to the source-drain metal electrode layer 710 a, 710 bwhile the lower electrode 707 may be laterally coupled to the gateelectrode 714, or other suitable electrodes in the device structure 750.The capacitor structure 712 formed in the device structure 750 may be astorage capacitor that may improve the display device electricalperformance. It is noted that the capacitor structure 712 may be formedin any location suitable in the device structure 750 as needed fordifferent device performance requirements.

In another example depicted in FIG. 7B, a capacitor structure 722,similar to the capacitor structure 712 depicted in FIG. 7A, may beformed with different dimensions and/or profiles of the composite filmlayer 502 severing as a capacitor layer 720 formed between the upperelectrode 710 and the lower electrode 707. Unlike the capacitor layer713 extends from the area above the gate electrode 714 to the areabetween the upper and the lower electrode 710, 707, the capacitor layer720 depicted in FIG. 7B is formed substantially in the area between theupper and the lower electrodes 710, 707. Thus, an interlayer insulator724 comprising silicon oxide or silicon oxide may be formed on the gateinsulting layer 706 surrounding the capacitor structure 722. Thecomposite film layer 502 or the high dielectric constant material layer308 formed as the capacitor layer 720 in the capacitor structure 722 mayhave a bottom surface in contact with the lower gate insulating layer706 as needed. The interlayer insulator 724 may be in a single layerform, as depicted in FIG. 7B, or in multiple layer form as needed.

It is noted that the composite film layer 502 or the high dielectricconstant material layer 308 formed by the process 200 or 300respectively may be utilized to form the capacitor layer 720, gateinsulating layer 706, as indicated in the circles of FIG. 7B, apassivation layer or any other suitable layers that require insulatingmaterials in the TFT device structures 750 including LTPS TFT for LCD orOLED TFT as needed.

It is noted that the upper electrode 710 and the lower electrode 707utilized to form the capacitor structures 722, 712 may also be pixelelectrodes and/or common electrodes as needed.

FIG. 8 depicts yet another example of a TFT device structure 850.Similar to the structure described above, the device structure 850includes a regular interlayer insulator 820 disposed on the gateelectrode 714. A passivation layer 822 may be formed on the interlayerinsulator 820. Another portion of the source and drain region 802(electrically connected to the source and drain region 709 a, 709 b) isshown on the optional insulating layer 704. Another portion of thesource-drain metal electrode layer 810 (electrically connected to thesource-drain metal electrode layer 710 a, 710 b) is disposed on andelectrically coupled to the source and drain region 802. A pixelelectrode 808 may be electrically connected to the source-drain metalelectrode layer 810, 710 a, 710 b. In this particular example, a portionof the gate insulating layer 706 passes through and between the gateelectrode 714 and the channel region 708, extending to the area abovethe source and drain region 802. In one example, the gate insulatinglayer 706 may be the composite film layer 502 having the first layer 510and the second layer 512 formed using the process 400 described abovewith referenced to FIG. 4, or the high dielectric constant materiallayer 308 in FIG. 3A-3C formed by the process 200 of FIG. 2. Anadditional electrode 804 is formed above the source and drain region 802and the gate insulating layer 706, forming a capacitor structure 806 inthe device structure 850. The additional electrode 804 formed on thegate insulating layer 706 (now also serves as a capacitor layer) may beelectrically connected to the gate electrode 714. Thus, the additionalelectrode 804 and the source and drain region 802 along with the gateinsulating layer 706 formed therebetween form the capacitor structure806 in the device structure 850. Similarly, the gate insulating layer706, now also serves as a capacitor layer, may be in form of any of thelayers as needed.

It is noted that the source-drain metal electrode layer 710 a, 710 b,810, the pixel electrode 808, the common electrode, the gate electrode714, the upper electrode 710, the lower electrode 707, the top electrode604, the bottom electrode 602, additional electrode 804 and anyelectrodes in the device structures may be any suitable metallicmaterials, including transparent conductive oxide layer (such as ITO orthe like), silver nano ink, carbon nano tube (CNT), silver nano ink andCNT, graphene, aluminum (Al), tungsten (W), chromium (Cr), tantalum(Ta), molybdenum (Mo), copper (Cu), TiN, MoO₂, MoN_(x), combinationthereof or other suitable materials.

It is noted that the structures above the passivation layer 822 in FIG.8 or the planarization layer 735 in FIGS. 7A-7B are eliminated for sakeof brevity. However, in some exemplary device structures, an additionalOLED or LCD devices, or other suitable devices may be formed above thepassivation layer 822 or the planarization layer 735 to form othersuitable flexible mobile display devices, such as LTPS OLED displaydevices with touch screen panels as needed.

Thus, the methods described herein advantageously improve the electronstability, electrical performance, low leakage and good film stackintegration of display device structures by controlling the materials,particular a high-k material comprising ZrO₂ with aluminum dopantsformed by either an ALD or PE-ALD process or a composite film layerhaving a first portion of a high-k material comprising ZrO₂ layer and asecond portion of a high-k material comprising ZrO₂ with aluminumdopants formed by either an ALD or PE-ALD process, and structures of agate insulating layer, capacitor layer, interlayer insulator,passivation layer, insulating materials in the display devices, alongwith a dielectric layer formed as a capacitor in the display deviceswith desired high electrical performance.

While the foregoing is directed to embodiments of the presentdisclosure, other and further embodiments of the disclosure may bedevised without departing from the basic scope thereof, and the scopethereof is determined by the claims that follow.

What is claimed is:
 1. A thin film transistor structure comprising: adielectric layer formed on a substrate, wherein the dielectric layer isa zirconium containing material comprising aluminum; and gate, sourceand drain electrodes formed on the substrate, wherein the gate, sourceand drain electrodes are formed above or below the dielectric layer. 2.The structure of claim 1, wherein the dielectric layer is a compositefilm layer having a first layer formed by the zirconium containingmaterial comprising aluminum and a second layer formed by a zirconiumcontaining material.
 3. The structure of claim 2, wherein the firstlayer comprising the zirconium containing material comprising aluminumhas an amorphous structure.
 4. The structure of claim 2, wherein thesecond layer comprising the zirconium containing layer has a crystallinestructure.
 5. The structure of claim 2, wherein the first layer is analuminum doped ZrO₂ layer having a dielectric constant between about 15and
 25. 6. The structure of claim 2, wherein the second layer is a ZrO₂layer having a dielectric constant between about 25 and about
 50. 7. Thestructure of claim 1, further comprising: a capacitor layer formed onthe gate electrode, wherein the capacitor layer is fabricated from azirconium containing material comprising aluminum or the capacitor layeris a composite film layer having a first portion fabricated from azirconium containing material comprising aluminum and a second portionfabricated from the zirconium containing material.
 8. The structure ofclaim 7, wherein the dielectric layer or the capacitor layer is formedby an atomic layer deposition process.
 9. The structure of claim 1,wherein: the zirconium containing material comprising aluminum has anamorphous structure; or the zirconium containing material comprisingaluminum is aluminum doped ZrO₂; or the zirconium containing materialcomprising aluminum is formed by an ALD process or a PE-ALD process; orthe zirconium containing material comprising aluminum has an aluminumconcentration between about 6 atm % and about 20 atm %.
 10. A method forforming a composite film layer for display devices, comprising:performing an ALD process to form a composite film layer comprising afirst layer and a second layer disposed on a substrate, the first layercomprises a doped aluminum zirconium containing layer formed on thesubstrate and the second layer comprises a zirconium containing layer.11. The method of claim 10, wherein the composite film layer is utilizedas a capacitor layer or a gate insulating layer in a display device. 12.The method of claim 10, wherein the first layer of the composite filmlayer is formed by alternatively providing an aluminum containingprecursor and a zirconium containing precursor to the substrate to formthe first layer.
 13. The method of claim 12, further comprising:providing an oxygen containing gas with the aluminum containingprecursor and the zirconium containing precursor or between each pulseof the aluminum containing precursor and the zirconium containingprecursor.
 14. The method of claim 13, wherein: the first layer is analuminum doped ZrO₂ layer with a dielectric constant between about 15and 25; or the second layer is a ZrO₂ layer with a dielectric constantbetween about 25 and about 50; or the first layer has an amorphousstructure and the second layer has a crystalline structure.
 15. A devicestructure utilized in a display device, comprising: a capacitorstructure having a capacitor layer formed between two electrodes in adisplay device, wherein the capacitor layer is an aluminum doped ZrO₂layer having an amorphous structure with a dielectric constant betweenabout 15 and about 25.